Maternal pro-inflammatory status in obesity regulates placental function

描述（由申请人提供）：超过60%的美国妇女进入妊娠超重或肥胖，胎儿过度生长在这些妊娠中很常见。胎儿过度生长增加了创伤性出生损伤的风险，并使婴儿在童年和以后的生活中容易患上肥胖症、糖尿病和高血压。超重/肥胖妇女胎儿生长增加的机制在很大程度上是未知的。我们的整体模型是，超重/肥胖女性中促炎细胞因子、瘦素和游离脂肪酸（FFA）水平的增加导致胎盘中TNF-和IL-6释放的增加。我们认为这些细胞因子刺激氨基酸转运蛋白的表达和活性，从而在体内增加对胎儿的营养输送，最终促进胎儿生长。为了解决这个模型，我们的中心假设是FFA通过多种信号通路刺激胎盘氨基酸运输，包括与Toll样受体4的结合，导致MAP激酶和NF的激活，从而促进IL-6等细胞因子的产生。我们进一步提出，由滋养细胞产生并在母体血浆中循环的细胞因子，通过影响特定氨基酸转运异构体的转录、翻译和/或膜运输，部分由STAT3介导，从而上调滋养细胞氨基酸转运。我们将在三个具体目标中解决这一中心假设：确定高母体体重指数（BMI）对关键细胞内信号通路和胎盘营养转运能力的影响。我们将招募75名瘦、超重和肥胖孕妇，测量胎盘中关键细胞内信号通路和营养转运蛋白的表达和活性，并将其与母体BMI和代谢参数相关联。2. 建立FFA对胎盘细胞因子产生的影响，并明确介导这种影响的细胞内信号通路。使用原代人滋养层细胞和siRNA技术，我们将描绘连接FFA增加细胞因子释放的细胞内信号通路。3. 确定促炎细胞因子对胎盘氨基酸运输的影响，并确定涉及的细胞内信号传导机制。关键细胞内信号分子的作用，如STAT 3，将在培养的人原代滋养细胞中使用siRNA方法进行研究，我们将研究胎盘氨基酸转运能力的三个水平的潜在调节：基因转录，蛋白质翻译和膜运输。我们的初步数据有力地支持了我们的中心假设。拟议的研究具有创新性，因为它们有望确定肥胖的母体代谢紊乱与胎盘功能改变之间的机制联系，胎盘功能改变会增加向胎儿输送营养物质。这项研究的意义在于，它将提供关于胎儿过度生长机制的新信息，这可能允许开发新的干预策略，以减少胎儿过度生长及其短期和长期的健康后果。

DESCRIPTION (provided by applicant): More than 60% of American women enter pregnancy overweight or obese and fetal overgrowth is common in these pregnancies. Fetal overgrowth increases the risk for traumatic birth injuries and predisposes the baby for development of obesity, diabetes and hypertension in childhood and later in life. The mechanisms underlying the increased fetal growth in overweight/obese women are largely unknown. Our overall model is that increased levels of pro-inflammatory cytokines, leptin and free fatty acids (FFA) in overweight/obese women cause an increase in TNF- and IL-6 release from the placenta. We propose that these cytokines stimulate amino acid transporter expression and activity, which in vivo will result in increased nutrient delivery to the fetus and ultimately increased fetal growth. To address this model our central hypothesis is that FFA stimulate placental amino acid transport mediated by multiple signaling pathways including binding to Toll Like Receptor 4 resulting in activation of MAP kinase and NF which promotes production of cytokines such as IL-6. We further propose that cytokines, produced by the trophoblast and circulating in maternal plasma, up-regulate trophoblast amino acid transport by affecting transcription, translation and/or membrane trafficking of specific amino acid transporter isoforms, mediated in part by STAT3. We will address this central hypothesis in three specific aims: 1. Determine the impact of high maternal body mass index (BMI) on key intracellular signaling pathways and placental nutrient transport capacity. We will recruit 75 lean, overweight and obese pregnant women and measure expression and activity of key intracellular signaling pathways and nutrient transporters in placenta and correlate these to maternal BMI and metabolic parameters. 2. Establish the effect of FFA on placental cytokine production and define the intracellular signaling pathway mediating the effects. Using primary human trophoblast cells and siRNA techniques, we will delineate the intracellular signaling pathway linking FFA to increased cytokine release. 3. Determine the effect of pro-inflammatory cytokines on placental amino acid transport and identify the intracellular signaling mechanisms involved. The role of key intracellular signaling molecules, such as STAT 3, will be investigated employing siRNA approaches in cultured human primary trophoblast cells, and we will examine three levels of potential regulation of placental amino acid transport capacity: gene transcription, protein translation and membrane trafficking. Our preliminary data give strong support for our central hypothesis. The proposed studies are innovative because they are expected to identify a mechanistic link between the perturbed maternal metabolism in obesity and alterations in placental function, which increases nutrient delivery to the fetus. The significance of this study is that it will provide novel information on the mechanisms underlying fetal overgrowth, which may allow for the development of new intervention strategies in order to reduce fetal overgrowth and its' short- and long-term health consequences. PUBLIC HEALTH RELEVANCE: Overweight and obese women often deliver large babies, which have a high risk to develop obesity, diabetes and hypertension already in childhood. We propose that changes in placental nutrient transport constitutes an important mechanism by which maternal obesity leads to increased birth weight. This is highly relevant to public health since this new information may lead to novel intervention strategies to alleviate fetal overgrowth, which could lessen the epidemic of obesity and diabetes in the next generation.